feat: call generate image API if isImageGeneration is true.

[agatha197]

Add Image Generation Feature to LLM Chat Component

This PR adds image generation capabilities to the LLM Chat Card component, allowing users to generate images from text prompts using a Stable Diffusion endpoint.

Key Changes:

• Added image generation functionality via new isImageGeneration prop
• Implemented generateImage function to handle image generation requests
• Added loading state for image generation process
• Modified message handling to support generated image attachments
• Added visual indicator for image generation feature

Checklist:

• Documentation
• Test case: Verify image generation with sample prompt
• Test case: Verify loading states during generation
• Test case: Verify error handling for failed requests

Review Requirements:

• Endpoint: https://stable-diffusion-3m.asia03.app.backend.ai/generate-image
• Access key configuration required for image generation
• Verify base64 image rendering in chat interface

[agatha197]

Warning

This pull request is not mergeable via GitHub because a downstack PR is open. Once all requirements are satisfied, merge this PR as a stack on Graphite.
Learn more

• feat: call generate image API if isImageGeneration is true. #3001 👈 (View in Graphite)
• add(FR-261): draft for model player UI derived from WebUI #2878
• main

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